The present invention is directed to a label laminate for labeling containers, and more particularly to a label laminate for applying decorative and/or informational labels to glass containers. Still more particularly, the invention is directed to a label composite which applies only the inks for the graphics.
Glass containers are currently labeled in three different ways. The predominant method is printed paper labels glued to the container at the time of filling and sealing. Such labels offer almost unlimited art potential and are commonly used on food, and both returnable and non-returnable beverage containers. This is the lowest cost technique, but offers little resistance to label damage from handling and exposure to moisture or water, and may not survive the washing procedures required of a returnable container, thereby requiring re-labeling.
A second, and more recently developed, container labeling technique is that of applying a thin styrofoam label to cover the container from shoulder to heel, with the decorative and/or informational material being printed on a more dense outer skin of the styrofoam label. This is widely used on lighter-weight one-way bottles common in the beverage industry. It offers some impact resistance and a large surface area for printing product information and instructions, as well as company logos. It is, however, more costly than the paper label, has little durability, becomes easily soiled, and will not survive the alkali washing of a returnable beverage container, or the pasteurization required by some beverage containers. Also, because the printing surface is relatively rough, high definition printing is not possible.
A third container labeling technique is that of printing ceramic ink directly on the container surface using a screen printing technology. While the label appearance is generally good, the technique is typically limited to two or three colors due to cost considerations. A recent development is the preprinting of a ceramic ink decal which is then transferred to the glass container surface. This permits high definition printing and offers greater opportunities for color and art variety. Fired ceramic inks are extremely durable and will survive the alkali washing processes required of a returnable container.
However, both the direct printing ceramic ink and ceramic ink decal techniques require subsequent high temperature firing to fuse the ink to the glass substrate. In addition, while the preprinted ceramic ink label reduces the technical problems somewhat, both techniques require extreme attention to detail, a high level of maintenance and are run off-line at slow speed, with high labor costs. Due to the high cost, ceramic inks are the least commonly used labeling technique.
It is common practice in the glass container industry to treat the outer surface of the containers with materials to counteract the effects of high glass-to-glass friction experienced on freshly manufactured glass products. Glass containers are conveyed with a great deal of glass-to-glass contact and at times considerable line pressure. Without treatment there is considerable visible scratching which may result in breakage. It is common to surface treat at two locations in the operation. Immediately after forming and before lehring, the containers pass through a vapor which leaves a tin oxide film bonded to the surface. After lehring the containers are sprayed with a dilute water solution of a material which after evaporation of the water leaves a film to provide surface lubricity. Of the two treatments the tin oxide film is most costly, both for materials and system maintenance. The lubricity of the second film, though needed to prevent surface damage, may cause problems in subsequent labeling of the container.
There is an ongoing program in the container industry to reduce the weight of the container by reducing wall thickness, but still maintain acceptable product strength for both the internal pressures of carbonated beverages and the impact strength to survive handling damage in the filling operations, in the market place and by the consumer. The benefits of reduced weight are economic: lower glass melting fuel and material costs, higher container manufacturing speeds (lower cost) and reduced product shipping costs.
It is an object of the present invention, with certain variations, to overcome the above-described disadvantages of prior art labeling techniques and to offer solutions to the above-described container industry problems.
More particularly, it is an object of this invention to provide a label which is durable, highly impact resistant and yet permits high definition label printing.
It is a further object of this invention to provide an efficient labeling-technique for applying the improved label in line with the container manufacturing process, e.g., at line speeds of 400 containers a minute and above.
These and other objects are achieved according to the present invention by a label laminate wherein a removable backing layer is reverse printed with, e.g., a vinyl, or acrylic ink which is then cured and the printed ink overprinted with adhesive. The label is then applied to the container with its adhesive surface in contact with the container, and the backing layer is separated from the label, e.g., by the application of heat, while concurrently the ink bonds to the container. The labeled container is then applied with a suitable coating, which is then cured. The printing process provides the desired high definition printing capability, and the coating provides the required degree of impact resistance and durability.
It is a further object of the invention to eliminate the cost of tin oxide coating. Because the coating provides impact resistance and durability, it is no longer necessary to provide the tin oxide film prior to container lehring. Instead, a token amount of lubricating film is applied after annealing. This is preferably a film compatible with the adhesion materials on the label inks and with the coating, although it could alternatively be a film readily removed by oxidizing flame treatment prior to labeling. This lubricating film is sufficient to enable damage-free conveying from the lehr, through the inspection stations and into the labeling machine staging area.
Yet another object of this invention is to foster continued further reduction in container weight. It has been demonstrated that a container entirely coated with a nominal 0.6 mil of the coating will survive a 30-40% increase in fracture impact over an uncoated container.
It is also well known that considerable glass surface damage occurs throughout the container handling cycle including bulk and case packing at the container manufacturer. At the container filling operations the handling surface damage is severe also. Because the coating provides a much greater degree of surface protection, container failure from surface damage would be greatly reduced. The applied layer of coating is complete over the entire container surface including the label, without voids or discontinuities. Further reductions in wall thickness without compromising container strength are therefore possible. These reductions have value in increasing container manufacturing speeds, reducing fuel usage and material costs as well as reducing transportation costs.
The invention also provides a system for applying the above-described label in an efficient manner so that it can be performed on-line. The efficiency is in part due to a novel label web indexing mechanism including a movable shuttle roller and alternating braking mechanisms at the supply and take-up ends. This is especially advantageous when simultaneously applying labels to a plurality of containers. The collection of the used web on a take-up reel permits re-use of the web for further cost savings. It is also possible to modify existing commercial container labeling systems to accomplish the label application, in which case the heat necessary for ink release and adhesive activation can be provided by heating the container to a temperature of 200xc2x0 F. prior to entering the labeling machine.